[0001] Air operated double diaphragm pumps have been a popular product for many years and
are widely used for the transfer of fluids and other uses. Such pumps are manufactured
by a variety of producers using a number of different designs. French patent publication
No. 2372363 discloses a washing machine water outlet pipe valve, which prevents return
flow of dirty water to a wash tub. The valve is a non-return valve comprising a hollow
valve head and finger-shaped guides within a housing. While a variety of such designs
have proven successful in the marketplace, it is always desirable to be able to reduce
the manufacturing cost of such products and in general that often means reducing the
parts count involved in such a product.
[0002] It is therefore an object of this invention to produce an air operated double diaphragm
pump which utilises a substantially lesser number of parts than prior art designs
and yet which is easily manufactured, easily assembled, and reliable in operation
for the consumer.
[0003] Towards this end, the design of the instant invention utilises a number of features
which serve to achieve this end and which make the product more user friendly and
adaptable for the end-user.
[0004] According to the present invention there is provided a check valve comprising:
a generally cylindrical cavity;
a central sealing disk;
a plurality of guide members extending radially and axially from said central sealing
disk, each said guide member having an outer diameter sized to slidingly fit within
said cylindrical cavity; and characterised by
a plurality of circumferentially extending spring loaded fingers on each said guide
member axially opposed said sealing disk which serve to bias said check valve into
a closed position check valve.
[0005] Thus, a one-piece check valve construction is utilised with the part having a central
sealing disk having a plurality of radially axially extending guide members extending
therefrom wherein each of the guide members has an outer diameter sized to slidingly
fit within a cylindrical cavity and each of the guide members having axially opposite
the sealing disk a plurality of circumferentially extending spring loaded fingers
which serve to bias the check valve into a closed position.
[0006] These and other objects and advantages of the invention will appear more fully from
the following description of an embodiment of the invention made by way of example
only in conjunction with the accompanying drawings wherein like reference characters
refer to the same or similar parts throughout the several views.
Figure 1 is a perspective view of the instant invention,
Figure 2 is a sectional view taken along line 2-2 of Figure 1.
Figure 3 is a partially exploded view of the manifold base and check valves.
Figure 4 is a plan view of the center section and diaphragms.
Figures 5 to 8 show the air valve in its sequence of operation.
Figure 9 is a sectional view taken along line 9-9 of Figure 1.
Figure 10 is a perspective view showing the valve carriage and valve block.
[0007] The instant invention generally designated 10 is shown in Figure 1 in perspective
and is comprised of a molded center section 12, two fluid end sections 14 and a valve
cover 16. In the preferred embodiment, center section 12 is molded of polyester resin
(PBT) Valox 357 - GE Plastic.
[0008] Cover 16 is fixed via conventional fasteners 18 to center section 12. Also affixed
via fasteners 18 to center section 12 are fluid housings 14. The main portion of the
pump comprised of center section 12 and fluid housing 14 is affixed to manifold base
20 also via fasteners 18. Manifold base 20 has fluid inlet and outlet passages 22
and 24 respectively located at each end to allow variety in plumbing arrangements.
[0009] Turning more specifically to Figure 3, check valves 26 are each comprised of a central
sealing area 26A having in the preferred embodiment four radially and axially extending
arms 26B extending therefrom and having a surface 26C which closely positions check
valve 26 in check valve passages 28. Spring loaded fingers 26D extend from either
side of arm 26B and act against the bottom or top of passage 28 to bias check valve
26 into the closed position where it will remain unless fluid pressure against sealing
area 26A should press it open. The radially extending guide members 26B also act as
a stop. The spring fingers 26D compress and the top of the guide arms 26C butts up
against the fluid cover 14 on the inlet check and the manifold base 20 on the outlet
check. This limits the check valve travel,
[0010] Members 30 on base 20 containing passages 28 are sealed to fluid body 14 by means
of seals 32 carried at the end thereof.
[0011] Returning to Figure 1, cover 16 has an air inlet 32 which pressurises the area underneath
cover 18. First and second auxiliary ports 54 and 56 respectively are located in the
side of center housing 14 for direct. connection of air from solenoid valves if it
is desired to have the pump controlled remotely rather than through the integral air
valve. The integral ports 54 and 56 make it easy to change a pump from air valve operated
to a remotely operated pump by removing the air valve cup and replacing it with an
air valve plug.
[0012] Turning to Figures 2, 9 and 10, the air valve assembly generally designated 34 is
comprised of a valve carriage 36 which has generally cylindrical end portions 36A
having seals 36B thereon, a rectangular central aperture 36C which retains moveable
valve block 38. Valve block 38 has a lower sealing section 38A and a central section
38B within aperture 36C of carriage 36 which thereby allows valve block 38 to move
normal to the plane of Figure 2. This movement occurs due to pushing on block 38 by
means of pins 40 which are actuated by diaphragm mounting block 41 in the center of
diaphragm 42. In the preferred embodiment, valve block 38 is formed of 90 Durometer
XNBR (Carboxylated Nitrile) with 10% TFE powder to reduce friction.
[0013] As seen in Figure 2, air passages M1 and M2 connect to the main air chambers on the
inner side of diaphragm assemblies 42 for pressurising the air chambers with compressed
air as will be more fully described in the operation of the air valve hereinafter.
Passages P1 and P2 connect to air chambers 44 and 46 respectively, passages P1 and
P2 running as shown in the drawings as straight passages and thence are covered and
connected to chambers 44 and 46 by cover 16.
[0014] Valve block 38 is retained in place in valve carriage 36 by boss 16A on cover 16.
To disassemble the valve assembly, one merely need remove fasteners 18 from cover
16 and lift cover 16 off whereupon valve block 38 is lifted upwardly thereby allowing
valve carriage 36 to be slid out of center housing 16.
[0015] Figures 5 to 8 show views of the valve port surface 48 which has five ports therein.
Central exhaust port E is connected to the exhaust passage 50 while pilot ports P1
and P2 are connected to first and second ends respectively of the pilot valve carriage
36. Similarly, main ports M1 and M2 are connected to first and second diaphragm air
chambers respectively. The space 52 above the ports referred to is generally filled
with compressed air and ports which are not covered by the valve block 38 are pressurised
with the compressed air.
[0016] In general, two adjacent ports and the exhaust port E are always covered and connected
at one time while the other two adjacent ports are fed with compressed air. If we
start with the valve block 38 in the upper right hand position as shown in Figure
5, ports M2 and P1 are connected to exhaust port E while compressed air is fed to
ports M1 and P2. In this situation, the pilot valve carriage 36 is at the upward end
of its travel while the diaphragms are approaching the left end of their travel whereupon
the pins 40 driven by the diaphragms 42 push the valve block 38 to the upper left
hand position shown in Figure 6 which connects compressed air to ports M1 and P1 while
exhausting ports P2 and M2. This pressurises the upper end of the pilot valve carriage
36 and moves the pilot valve carriage 36 downwardly and the valve block 38 into the
lower left hand position of Figure 7 whereupon compressed air is connected to ports
P1 and M2 and ports M1 and P2 exhaust.
[0017] At that point, the diaphragms are moving together to the right while the pilot value
carriage 36 is in the down position. As the diaphragms reach the rightward end of
their stroke, the valve block 38 is moved into the lower right hand position of Figure
8 whereupon compressed air is fed to ports P2 and M2 while ports P1 and M1 are exhausted.
This pressurises the lower end of the pilot valve carriage 36 and the pilot valve
carriage 36 and the valve block 38 move upwardly to the point where the description
started above.
[0018] It can be noted that a very low number of parts is required to produce this valve.
The ends of the chambers for the pilot valve carriage 36 are completed by the valve
cover 16 which also covers the top of the valve cavity at the same time.
[0019] The inlet threads on the manifold base are such that it allows use of either all
American pipe thread (NPT) or British standard pipe thread (BSP). This hybrid thread
may be formed in plastic parts and is intended to form a pressure tight joint with
either plastic or brass male pipe threaded fitting of either type thread. The thread
is defined as follows:
Major diameter |
13.16 mm (0.518") |
Pitch |
12.30 mm (0.4843" ) |
Minor Diameter |
11.45 mm (0.4506") |
Angle |
1 degree 47 minutes |
Threads per cm |
7.32 ( 18.6 threads per inch) |
Effective thread |
10.21 mm (0.402" ) |
[0020] The muffler 54 is best seen in Figure 9. Exhaust port E leads to cylindrical passage
56 which is divided into first and second portions 56A and 56B by divider 56C. The
passage is completed by a muffler area 58 in manifold base 20. Hence, exhaust flows
out port E, into first portion 56A and into muffler area 58 whereupon it flows upwardly
through second portion 56B and out through muffler outlet 60. This arrangement allows
substantial muffling at low cost and with little penalty to performance.
[0021] It is contemplated that various changes and modifications may be made to the pump
without departing from the scope of the invention as defined by the following claim.
[0022] The aforegoing description has been given by way of example only and it will be appreciated
by a person skilled in the art that modifications can be made without departing from
the scope of the present invention.